Adusting pliers for electrical spring contacts



April 11, 1950 F. s. CRAIG 2,503,557

ADJUSTING PLIERS FOR ELECTRICAL SPRING CONTACTS V 2 Sheets-Sheet 1 Filed Aug. 6, 1947 Z Fla. 1. u M

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lnvcntor April 11, 1950 F. s. CRAIG 2,503,657

ADJUSTING PLIERS FOR ELECTRICAL SPRING CONTACTS Filed Aug. 6, 1947 2 Sheets-Sheet 2 I ma.

ZO mg i w mtomeg Patented Apr. 11, 1950 ADJUSTING PLIERS FOR ELECTRICAL SPRING CONTACTS Frank s. Craig, Chili, N. Y., assignor to General Railway Signal Company, Rochester, N. Y.

Application August 6, 1947, Serial No. 766,531

1 Claim. 1

This invention relates to a means for initially setting and later adjusting the tension of electrical spring contact members, and more particularly relates to a mechanical device for evenly adjusting the spring pressures exerted by the plug members of a so-called plug coupler for quickly connecting or disconnecting electrical circuits. Such a plug coupler for a multiple number of connections has been shown and described in the prior patent to Oscar S. Field No. 2,217,219 dated October 8, 1940.

During the initial assembly of plug couplers of this character, the plug contact members are merely shaped to the extent to allow proper assembly on the plug board member. After assembly, each spring contact member is individually adjusted until it meets certain gauge requirements and spring tension specifications, so that when this plug board member is placed in contact with the socket board member of the complete plug coupler assembly, the various plug contacts enter their respective sockets with substantially the same uniform pressure exerted on each plug spring member.

However, it has been found in practice that r 1 when these units are put into service, such as in a railroad light signal as shown in the patent to Edmund W. Moore No. 2,239,336 dated April 22, 1941, or on a relay as shown in the patent to Oscar S. Field, No. 2,272,552 dated February 10, 1942, periodic inspection and replacing complete mechanisms causes the original adjustment of these plug contact members to become distorted, mainly in that the sides of the spring contacts become pressed too close together and tend to fit too loosely in its corresponding socket member, resulting in poor electrical contact and failure in its duty to carry the proper amount of current to any device "to which it may be connected.

One of the contributing factors to this distortion is that it was found necessary to use a relatively resilient spring material, especially in plug boards having several of these contact spring members. When a fairly hard spring material was used which would withstand much use, the pressure of the spring contacts added up to such a value that difiiculty was experienced in discon necting the two members of the plug coupler. Thus, it was found necessary in these couplers having a plurality of plugs to use a more resilient material which exerted less contact pressure per unit and consequently was more subject to distortion during usage. This situation resulted in requiring the frequent adjustment of the plug contact springs. v

One object of the present invention is to provide a simple and efiicient tool to, facilitate the adjustment of these plug contact members, which is especially desirable since most of this work has to be done in the field and sometimes under adverse weather conditions.

Another object of this invention is to make this tool adjustable so that the degree of spreading movement may beadjusted to suit different contacts having varying degrees of resiliency.

- Still another object of this invention is to provide a maximum-minimum gauge on the tool, so that it can readily be ascertained whether a contact spring is in need of adjustment and also whether the adjustment is correct after ithas been made.

Further objects, purposes, and characteristic features of the present invention will be pointed out as the description progresses.

In describing the invention in detail, reference should be made to the accompanying drawings in which:

Fig. 1 is a sectional view of the plug and socket components of a plug coupler of the type selected to illustrate the invention, these two components being shown in non-cooperating positions;

Fig. 2 is a cross sectional view of the coupler of Fig. 1 with its component parts shown in cooperating positions; v

Fig. 3 is a view of the plug component of the coupler and the contact adjusting tool of the present invention in position to initiate the adjustment of a spring contact plug member;

, Fig. 4 is a view similar to Fig. 3 except the contact adjusting tool is shown in an expanded position;

Fig. 5 is a perspective view of the contact adjusting tool of the present invention;

Figs. 6 and '7 are perspective Views which show the contact spring being gauged by the minimumand maximum gauge slots respectively which form a part of the contact adjusting tool; and

Figs. 8 and 9 are detail views of the expander cams which form a part of the contact adjusting tool; I r v Referring more particularly'to Figs. 1 and-2,

a plug coupler arrangement of the type shown" and described in the above mentioned Patent No.

2,217,219 has been illustrated as a quickly de-. tachable coupler with which the tool of the pres-- ent invention may be used. A brief descriptionv of this plug coupler should suffice, since reference may be made to this patent for a complete show-- ing and description. Principally, this plug coupler consists of a plug board PB and asocket..-

board SB. The plug board PB comprises a board I made up of the usual molded insulating plastic, having molded therein a series of slots and lugs to which are fastened the plug contacts P of general loop shape and wire terminals ii. The socket board SB also comprises a molded insulating board !2 having molded therein the socket members S. :Each: of the socket members S (see Fig.2) 'has two bored holes therein, located on either side of center, the hole I3 on the inside face forming a socket for the plug contact P and the hole on the outside face being ithreaded "to receive the screw [4 which clamps the terminal wires iii in place. It can.readily be seen that when the two boards PB and'SB arepushed'together the plug contacts P cooperate with the socket members S by entering their respective holes l3, and form an electrical path from the wire terminals I I through the plug contacts P, the socket members S and the screws m to the other terminalwire 'l 5.

Referring now to 'Figs. "3, *4, and particularly Fig.5, the contact adjusting tool of the present invention is "shaped somewhat similar to a pair of pliers and is -adaptedto be Worked by hand. This tool comprises two halves L and R which are=cast from the samepattern'or mold. Each of these halves consists of an arm portion is, a 'pivotbearing portion H, a gauge portion 18 at the-handle endyexpander cams 20 at the head end, and =a'limiting fiange lfi-also at the head end betweentheexpander earns 26 and the bearing portion 11. These two halves L and R are positioned face'to face with respect to each other, and are pivoted together'at the overlapping pivot bearing portions I! about a common bolt 2!, which bolt is'lockedwith a nut and peaned over in'the usual way fsee'Fig.-9) The expander cams 20 are maintained in a closed position by means of a U-shaped leaf spring 22 which ispositioned between the two 'arms-i'fiandriveted at one end to the right hand arm ii. The open position of the expander'cams' 20 is limited by a stop screw 2-3 which isadjustably positioned in a threaded hole in 'the-lefthand arm 16 and locked in place by a nut 24*(see Fig; 4').

Theexpander cams 20 are formed on both sides of an extending flange '25"(see--Figs. *8 and 9) and have a rounded area 20a at oneend and a partially-pointed area 'Zflb at the opposite end (see Fig. 8'). 'Thegeneral-sh'ape of these-cams 28 is such that when the adjusting tool is in the closed positionthecams'i'll 'on each of'the two halves L and R come together andform a contour which is of'a general'shapesimilar to the inside contour of the plug contact P, all as shown in Fig. 3. When the adjusting tool is operated to the open position as is the case when a plug'contact is being expanded as shown in'Fig.-4, it will be noted that the rounded areas '2l'ia-of the'cams 2'3 exert a pressure on the inside "surfaces of the plug contact P at "substantially a mid-point on each side, thus forcing the sides 'of the spring contact P outward. The'pointed areas 20b of the cams 2d and the limiting flange portions [9 position theplug contact P 'inthe 'a djusting'tool and determine "the point "at which the rounded areas Zila ofthe cams T20 bearagainstthe inside surfaces of'the plug contact spring. The pointed portions 201) of the expanding 'carns 2% also act to slightly expand the end portion of the plug contact spring as best seen in Fig. 4. "This is necessary since the plug aspring 1 might become too bluntLto be inserted into .its socket if it were expanded atitscenter.

Each of the gauge portions I8 located at the outer ends of the side arms l6, has a slot, one side of which has a shoulder thereon, thus forming a slot having two different widths, one width being termed the minimum gauge 26 and the other width being termed the maximum gauge 27. During original assembly or at any time while a plug coupler isiin service, it :can readily be determined if any of the plug contacts need adjustment by applying the gauges to the contacts as shown in Figs. 6 and 7. If the minimum gauge 2fi passescover the contact spring P without exerting any pressure, the contact should be .expanded so that it passes loosely through the maximum gauge .21. A contact thus adjusted will exert a noticeable pressure when again passed through zthezminimum gauge 26, and this pressure .is equivalent to the pressure exerted by a contact P when pressed into its cooperating socket S because the minimum gauge 26 simulates the size of a'socket. Actually, the minimum gauge '26 'isnot of a width corresponding tothe diameter of a socket-hole, but is'of a width corresponding to the distancebetween the :points on the inside of the socket holes where 'the flat contact springsengage the circumference of the holes.

As will be apparent from the foregoing description, when a contact adj-ustment'is necessary, the adjusting tool is-place'd in 'a cooperating position with the plug contact P as shown in Fig. 3 and the pressure exerted by the hand "on arms It opens the expander earns 20, whichcams in turn expand the contacts as shown in Fig.4. The amount of cam opening is limited because the stop screw 23 limits the movement of the arms l5. After the handpressure is released, the adjusting tool returns 'to its original position because of the pressure'exerted on the side arms It by the leaf spring 22. The-adjusting tool may then be removed and its attached gauges used to check the conditions of the contact thus adjusted.

As these contacts are madeof resilient mate rial, such as Phosphor bronze, or the like, and

tend'to flex back to their original position when the 'tool is removed, it can be seen that the amount of spread made with the tool and required for proper adjustment of the contact spring must be initially determined by trial until a proper position is found for the adjustable stop screw 23 which may then be locked in place with the nut After this adjustmet of the tool has once'been made, each of the plug contacts of a multiple plug coupler can be individually adjusted by-one simple operation. However, as noted hereinb'efore, different plug couplers may be encountered which contain plug contacts made of material having different degrees of resiliency. It will then be obvious that the degree of opening of the tool will require adjustment, as just explained, so that the proper adjustment can be made to these differentplug contacts.

Having described aitool for-readily and easily adjusting the contact'members of a plug-board arrangement of the type described as one embodiment of the present invention, it should be understood that variations can be in the shape and size or nature of the tool without departing from the'spirit or scope of invention.

It should furtherbe understood that the tool herein :provided canbe used for the adjustment of various types of spring contacts otherthan those shown, such as wire clips, terminal clips, or any spring snap fastener means of the loop spring type.

What I claim is:

A tool for setting the lateral spacing of the sides of an oblong loop contact comprising in combination, a pair of hand operable expansion pliers pivoted at an intermediate point to present jaw portions and handle portions, oppositely disposed oblong forming members rising from the sides of the jaw portions in a direction parallel to the pivot, said members having opposing fiat surfaces and outer curved or cam surfaces, said members being spaced from the pivot point, said members being adapted to be inserted before expansion of the pliers within the loop of a loop contact to be expanded, each of said members being formed to taper toward the pivot point whereby a forming surface is adapted to diminish the expansion of the loop of a loop contact gradually in the direction of said pivot point, and each of said members being of a length to bear against a substantial portion of the inner surface of one side of a loop contact upon expansion of the pliers, and stops on said jaw portions of said pliers between said members and said pivot point, said stops being spaced from said members only a sufficient amount topermit insertion of a loop contact over said members with the end of the loop passing between the members and the stop, whereby the spreading of the sides of the loop of a loop contact can be accomplished by expansion of the pliers to materially increase the overall contact pressure of a loop contact without materially deforming or shortening the loop.

FRANK S. CRAIG.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 505,835 Kulp et al. Oct. 3, 1893 884,821 Huhta Apr. 14, 1908 1,319,007 Kind Oct. 14, 1919 1,726,582 Ottinger Sept. 3, 1929 2,396,619 Strayer Mar. 12, 1946 

